1. Field of the Invention
The present invention concerns improvements to an espresso coffee machine, more especially, an espresso coffee machine fitted with a controlled temperature dose-holder.
In the present description the dose-holder is intended as that part of an espresso coffee machine suited to containing a prepackaged dose of coffee or else a dose of loose coffee from which a coffee beverage may be brewed.
One should, first of all, recall that according to the prior art, a dose-holder of an espresso coffee machine also comprises a peripheral structure, conventionally called &lt;&lt;cup&gt;&gt;, in which there is an internal structure that carries the dose of coffee, that is conventionally called &lt;&lt;filter&gt;&gt;, when it must hold a dose in the form of loose coffee, or in that of a disk in which the coffee is held between two filter-paper elements, or else is conventionally called &lt;&lt;lodging&gt;&gt; when it must hold a dose in the form of &lt;&lt;cartridge&gt;&gt; or &lt;&lt;capsule&gt;&gt;, and hence, that the coffee beverage brewed by percolation, that is by the passage of hot water under pressure through the dose of coffee, comes into contact with the internal surface of the cup before falling into the coffee-cup, and for this reason, there is a thermal relationship between the temperature of the beverage just brewed from the dose of coffee and the temperature of the cup such as to affect the quality of the beverage.
Now, it is well known that in order to prepare a good espresso coffee it is at least necessary, on one hand, that the coffee be of good quality, properly roasted, ground, dosed, packaged and pressed, and, on the other hand, that the machine features proper technical characteristics in terms of geometry, construction, hydraulic sealing, etc., and that it must be controlled so as to provide the right pressure and temperature; another condition is that the active parts of the machine (boiler and heat-exchanger, percolation head and dose-holder) are kept at the correct temperature and this sets a problem for the dose-holder that is passively heated by heat transferred from the percolation head of the machine, and, essentially, it is the most peripheral active part of the machine and gets heated later.
Espresso coffee machines according to the state of the art, are, upon being switched on, unable to ensure the thermal conditions suited to obtaining a good coffee unless one applies the method of bringing the machine to standard by a preliminary empty-run, that is allowing hot water or vapour to run through the dose holder bringing it to a temperature close to that of the hot water that runs through it during the brewing of coffee. Consequently the first cup, or cups, of coffee brewed after a period of inactivity of the machine do not provide satisfactory results, in fact, a temperature of the dose-holder conveniently close to that of the percolated coffee is the one that better enhances the formation, on the surface of the coffee, of the emulsion phase that is typical of espresso coffee that is called &lt;&lt;cream&gt;&gt;, and of which the quantity, creaminess and durability are especially appreciated by consumers.
Please note that known coffee machines are equipped only to indicate the temperature of the hot water generator, among the active parts, and not others, such as, the dose-holder.
2. Description of Related Art
Documents DE-U-9203171 and Patent Abstract of Japan, vol. 96 n.degree. 10, 31, 10, 96, JP-A-08 164074 are known that disclose, respectively, a container for preparing coffee or tea of the "thermos" type and a percolator pot for extracting drinkable material both provided with temperature sensor(s) able to indicate the temperature of the beverage once the latter is into the container or pot; the scope of said contrivances is the one of allowing a user to know the temperature of the brewed beverage, whilst the scope of this present invention is to let a user wait for the dose-holder reaching a desired temperature after the machine is switched on and before starting a brewing operation.